You would have to change the POI icons for the gas stations. There is a file called Branding.zip in the "My Flash Disk/APL2/iGo" folder from Pioneer, with plain vanilla basic icons. You have to replace this file with a custom one.
Search Branding.zip in the forum, under Hacks/Mods, there are two threads by VBLUE42 on this matter.
The icons are cool .... but the size of the 3D gas stations is small